1. Field of Invention
The invention relates to a control device of the heating ventilation air conditioning (HVAC) system and, in particular, to a HVAC system control device with two processors.
2. Related Art
With the development of heating ventilation air conditioning (HVAC) industry, high-rise buildings, department stores, factories, and hotels use HVAC systems to adjust indoor temperature for a more comfortable environment. The HVAC systems include inverters and air conditioners. By detecting the ambient temperature and moisture, the operations of the Inverters and air conditioner are controlled accordingly. However, manufacturers of the Inverters and air conditioners often over-complicate the control method of the HVAC systems in fear of the problems that their kernel techniques may be released, the control software is difficult to integrate, and the integration cost is too high.
Currently, most of the HVAC system control devices use their own control circuit board (that is, the Inverters and the air conditioners are independently controlled). Therefore, there are drawbacks such as larger circuit sizes and higher manufacturing costs. Communications and control of the two control circuits are done via an external communication circuit (e.g., the RS-232 port). In addition to a longer communication path, it is also susceptible to noises. In the worst case, it may cause the devices to act incorrectly.
FIG. 1 shows a system block diagram of the currently used control device for HVAC systems. The Inverter processor 1a is disposed on the circuit board 1 and communicates with the air conditioner processor 2a disposed on the circuit substrate 2 via the external communication circuit 3. The Inverter processor 1a and the air conditioner processor 2a process respectively dedicated kernel control software, peripheral software, and system software in order to control the Inverter and the air conditioner (not shown). For the convenience of illustration, other circuit blocks on the circuit board 1 and the circuit substrate 2 are not drawn.
Therefore, how to provide a control device that integrates the two processors at a lower cost is an important issue.